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Temperature and total white blood cell count as indicators of bacteremia
1Hospital for Sick Children, University of Toronto, Ontario, Canada.
Insights
Total white blood cell (WBC) count is a more accurate indicator of bacteremia in children than rectal temperature. A WBC count cutoff of 10,000/mm3 improves diagnostic specificity with minimal sensitivity loss.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Diagnostics
- Microbiology
Background:
- Bacteremia diagnosis in children with focal infections relies on indicators like temperature and white blood cell (WBC) count.
- Accurate differentiation between true bacteremia and inflammatory responses is crucial for appropriate treatment.
Purpose of the Study:
- To precisely quantify the accuracy of rectal temperature and total WBC count in diagnosing bacteremia in children.
- To compare the diagnostic utility of temperature increments versus WBC count for identifying bacteremia.
Main Methods:
- Utilized receiver-operating-characteristic (ROC) curves to analyze sensitivity and specificity.
- Evaluated 955 children (3-36 months) with fever (≥39.0°C) and focal bacterial infections.
- Analyzed blood cultures and WBC counts, with 27 cases of bacteremia identified.
Main Results:
- WBC count demonstrated significantly better diagnostic information than temperature increments.
- A WBC count cutoff of 10,000/mm3 yielded 92% sensitivity and 57% false-positive rate.
- Combining WBC count and temperature did not improve diagnostic accuracy over WBC count alone.
Conclusions:
- Increments in temperature above 39.0°C offer limited diagnostic specificity for bacteremia at the cost of sensitivity.
- Total WBC count is a superior indicator for bacteremia diagnosis in this pediatric population.
- A WBC count cutoff of 10,000/mm3 enhances specificity with minimal impact on sensitivity, potentially reducing unnecessary blood cultures.
Abstract:
This study was designed to quantify more precisely the accuracy of magnitude of rectal temperature and total white blood cell (WBC) count as indicators of bacteremia in children with an obvious focal bacterial infection. A total of 955 children, aged 3 to 36 months, who had rectal temperature greater than or equal to 39.0 degrees C and were seeking care at either of two urban pediatric emergency departments had blood drawn for culture; 885 had blood drawn for WBC count. Twenty-seven had bacteremia. Various combinations of temperature and WBC count were selected to construct receiver-operating-characteristic curves by plotting sensitivity vs false-positive rate (1 - specificity). The receiver-operating-characteristic curve of WBC count provided significantly better diagnostic information than the curve for temperature increments above 39.0 degrees C. Each increment of 0.5 degrees C led to large decrements in sensitivity and false-positive rates. At a WBC count cutoff of 10,000/mm3, the sensitivity was 92% while the false-positive rate was 57%. Using this cutoff point, the clinician could have avoided performing 368 of 955 blood cultures and missed only 2 of 26 children with bacteremia. Receiver-operating-characteristic curves combining WBC count and temperature increments above 39.0 degrees C provided no better diagnostic information than that of WBC count at a temperature cutoff of 39.0 degrees C. It is concluded that increments in temperature above 39.0 degrees C provided additional diagnostic specificity for bacteremia only at the expense of unacceptable decreases in sensitivity. Total WBC count provided better information. A WBC count cutoff of 10,000/mm3 increased specificity with minimal decrease in sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)